All Exams Test series for 1 year @ ₹349 only
Question

By Interchanging the given two numbers which of the following equation will be not correct?

3 and 4

This question was previously asked in
SSC CGL 2022 Tier-II (Paper 2 JSO) Previous Year Paper (04-Mar-2023)
The correct answer is

4 × 6 – 3 + 9 ÷ 1 = 25

Understanding the Problem: Interchanging Numbers in Equations

The question asks us to examine four mathematical equations. For each equation, we need to swap the positions of the numbers 3 and 4. After performing this interchange, we must evaluate the modified equation using the correct order of operations (like BODMAS or PEMDAS) and check if the resulting value matches the original result given in the equation. The task is to identify which of the given equations becomes incorrect after this interchange of 3 and 4.

To solve this, we will go through each option one by one, perform the interchange, and then evaluate the equation.

Order of Operations (BODMAS/PEMDAS)

Remember the order of operations to correctly evaluate mathematical expressions:

  • B/P: Brackets/Parentheses first
  • O/E: Orders/Exponents (powers, square roots) next
  • D/M: Division and Multiplication (from left to right)
  • A/S: Addition and Subtraction (from left to right)

Analyzing Each Equation by Interchanging 3 and 4

Option 1 Analysis: Check Equation Correctness

The original equation is: \(3 + 5 \times 4 - 6 \div 2 = 16\)

Now, we interchange 3 and 4. The new equation becomes:

\(4 + 5 \times 3 - 6 \div 2\)

Let's evaluate this using BODMAS:

  • First, perform Multiplication and Division from left to right:
    • \(5 \times 3 = 15\)
    • \(6 \div 2 = 3\)
  • The equation is now: \(4 + 15 - 3\)
  • Next, perform Addition and Subtraction from left to right:
    • \(4 + 15 = 19\)
    • \(19 - 3 = 16\)

The result after interchanging 3 and 4 is 16.

Comparing with the original result (16), we see that \(16 = 16\).

Conclusion for Option 1: The equation remains correct after interchanging 3 and 4.

Option 2 Analysis: Identifying the Incorrect Equation

The original equation is: \(4 \times 6 - 3 + 9 \div 1 = 25\)

Now, we interchange 3 and 4. The new equation becomes:

\(3 \times 6 - 4 + 9 \div 1\)

Let's evaluate this using BODMAS:

  • First, perform Multiplication and Division from left to right:
    • \(3 \times 6 = 18\)
    • \(9 \div 1 = 9\)
  • The equation is now: \(18 - 4 + 9\)
  • Next, perform Addition and Subtraction from left to right:
    • \(18 - 4 = 14\)
    • \(14 + 9 = 23\)

The result after interchanging 3 and 4 is 23.

Comparing with the original result (25), we see that \(23 \neq 25\).

Conclusion for Option 2: The equation becomes incorrect after interchanging 3 and 4.

Option 3 Analysis: Check Equation Correctness

The original equation is: \(3 \times 7 - 8 \div 2 + 4 = 27\)

Now, we interchange 3 and 4. The new equation becomes:

\(4 \times 7 - 8 \div 2 + 3\)

Let's evaluate this using BODMAS:

  • First, perform Multiplication and Division from left to right:
    • \(4 \times 7 = 28\)
    • \(8 \div 2 = 4\)
  • The equation is now: \(28 - 4 + 3\)
  • Next, perform Addition and Subtraction from left to right:
    • \(28 - 4 = 24\)
    • \(24 + 3 = 27\)

The result after interchanging 3 and 4 is 27.

Comparing with the original result (27), we see that \(27 = 27\).

Conclusion for Option 3: The equation remains correct after interchanging 3 and 4.

Option 4 Analysis: Check Equation Correctness

The original equation is: \(9 \times 3 \div 6 + 4 - 8 = 1\)

Now, we interchange 3 and 4. The new equation becomes:

\(9 \times 4 \div 6 + 3 - 8\)

Let's evaluate this using BODMAS:

  • First, perform Multiplication and Division from left to right:
    • \(9 \times 4 = 36\)
    • \(36 \div 6 = 6\)
  • The equation is now: \(6 + 3 - 8\)
  • Next, perform Addition and Subtraction from left to right:
    • \(6 + 3 = 9\)
    • \(9 - 8 = 1\)

The result after interchanging 3 and 4 is 1.

Comparing with the original result (1), we see that \(1 = 1\).

Conclusion for Option 4: The equation remains correct after interchanging 3 and 4.

Summary of Results after Interchanging 3 and 4

Option Original Equation Equation After Interchanging 3 and 4 Calculated Result Original Result Correct After Interchange?
1 \(3 + 5 \times 4 - 6 \div 2 = 16\) \(4 + 5 \times 3 - 6 \div 2\) 16 16 Yes
2 \(4 \times 6 - 3 + 9 \div 1 = 25\) \(3 \times 6 - 4 + 9 \div 1\) 23 25 No
3 \(3 \times 7 - 8 \div 2 + 4 = 27\) \(4 \times 7 - 8 \div 2 + 3\) 27 27 Yes
4 \(9 \times 3 \div 6 + 4 - 8 = 1\) \(9 \times 4 \div 6 + 3 - 8\) 1 1 Yes

Based on our analysis, the equation in Option 2 is the only one that is not correct after interchanging the numbers 3 and 4.

Conclusion

By carefully interchanging 3 and 4 and applying the order of operations (BODMAS/PEMDAS) to each equation, we found that only the equation from Option 2 resulted in a value different from the original equation's result. Therefore, the equation in Option 2 will be not correct after interchanging the given two numbers.

Revision Table: Understanding Interchanging Numbers

Concept Explanation Importance
Interchanging Numbers Replacing one specific number with another specific number wherever they appear in an expression or equation. Changes the values and potentially the outcome of calculations.
Order of Operations A set of rules (like BODMAS/PEMDAS) that dictate the sequence in which mathematical operations should be performed. Ensures consistent and correct evaluation of expressions.
Evaluating Equations Calculating the value of one side of an equation to check if it equals the other side. Used to determine if an equation is true or false.

Additional Information: Solving Equations with Number Swaps

Problems involving interchanging numbers are common in tests of numerical ability and logical reasoning. They require careful substitution and precise application of mathematical rules like the order of operations. When tackling such problems:

  • Read the instruction carefully: Which numbers are being interchanged? Where?
  • Rewrite the expression or equation after the interchange.
  • Strictly follow the order of operations (BODMAS/PEMDAS) during evaluation.
  • Perform calculations step-by-step to minimize errors.
  • Compare the final result with the target value (the original result in this case) to determine correctness.
  • These problems test attention to detail and fundamental arithmetic skills.
Was this answer helpful?

Similar Questions

  1. Which of the following interchange of numbers and mathematical signs would make the given equation correct?

    30 ÷ 6 × 4 + 15 - 35 = 25

  2. Select the correct combination of mathematical signs that can sequentially replace the * signs and make the equation correct.

    48 * 12 * 8 * 15 * 3 * 44

  3. By Interchanging the given two numbers which of the following equation will be not correct?

    9 and 6

  4. By Interchanging the given two numbers which of the following equation will be correct?

    2 and 8

  5. Which two signs should be interchanged to make the given equation correct?

    95 * 5 + 19 ÷ 2 − 21 = 36

  6. By interchanging the given two signs and numbers which of the following equation will be not correct?

    + and –, 3 and 5

  7. Select the correct combination of mathematical signs to sequentially replace the * signs and to balance the given equation.

    50 * 25 * 10 * 2 * 175

  8. Which two signs and two numbers should be interchanged in the following equation to make it correct?

    10 × 11 + 19 - 323 ÷ 3 = 50

  9. By interchanging the given two signs which of the following equation will be not correct?

    + and ÷

  10. By interchanging the given two signs and numbers which of the following equation will be not correct?

    × and +, 7 and 4

    I. 7 × 8 + 4 – 6 ÷ 3 = 57

    II. 4 × 8 – 9 ÷ 3 + 7 = 3


Important Questions from Logical Puzzle

  1. Seven persons P, Q, R, S, T, U and V like different watches namely W1, W2, W3, W4, W5, W6 and W7 (not necessarily in the same order). P and R do not like odd numbered watch. T likes W5. U does not like W2 or W3 or W6 or W7. P likes prime numbered watch. Q likes W4. S likes W2 or W7. Which of the following statement(s) is/are correct ?

    I. S likes W7.

    II. R likes W2.

    III. U likes W1.

    IV. V likes W3.

  2. If ‘+’ means ‘×’, ‘×’ means ‘÷’, ‘÷’ means ‘–’ and ‘–’ means ‘+’, then

    16 + 18 × 3 ÷ 6 = ?

  3. In a certain code language, ‘Today is last match’ is written as ‘Sa Te Mo Pt’, ‘Last king like your team’ is written as ‘De Ra Mo Lo Zs’, ‘Our team won today match’ is written as ‘Te Ra Pt Ae We’. What is the code for ‘Our won is Last’ in that code language?

  4. In a certain code language, ‘LETTER’ is written as ‘ZLZYIO’. What is the code for ‘ACTION’ in that code language?

  5. If A denotes ‘+’, B denotes ‘×’, C denotes ‘-’, and D denotes ‘÷’, then what will come in place of ‘?’ in the following equation?

    34 A 15 B 3 C 11 B 2 A (51 D 17) = ?

Need Expert Advice?
Upcoming Exams
SSC CGL
September 30, 2026
UPSSSC PET
October 23, 2026
Test Series
SSC CGL img
SSC
SSC CGL (Tier I + Tier II) 2026 Mock Test Series - Latest Pattern
2503 Tests 6 Tests Free
5389 Attempts
4.2(868)
English, Hindi

Start Your Preparation with Prepp Mobile App

Download the app from Google Play & App Store
Download the app from Google Play & App Store
Prepp Mobile App